1. Field of the Invention
The present invention relates to driving an LCD and particularly to an apparatus and method for charge sharing between source lines of the pixel array in a TFT-LCD.
2. Description of the Related Art
In general, a conventional TFT-LCD is operated by providing positive and negative video signals alternately to the liquid crystal on the basis of VCOM, however, resulting in flicker. To reduce the generation of flicker, a conventional TFT-LCD is employed one of a frame inversion, line inversion, column inversion and dot inversion shown in FIGS. 1A to 1D, respectively.
The frame inversion of FIG. 1A is a mode that the polarity of the video signal changed only when the frame is changed. The line inversion of FIG. 1B is a mode that the video signal's polarity is varied whenever the gate line GL changes. The column inversion shown in FIG. 1C converts the polarity of the video signal whenever the source line DL changes, and the dot inversion of FIG. 1D converts it whenever the source line DL, gate line GL and frame change. The image quality is satisfactory in the order of the frame inversion, line inversion, column inversion and dot inversion. When convert the video signal's polarity from positive to negative or from negative to positive, it cause power consumption. Therefore, the dot inversion causes higher power consumption.
FIG. 2 illustrate the video signal's polarity conversion in the conventional TFT-LCD. In FIG. 2, the video signal of two adjacent source line DL#1 and DL#2 convert polarity during asserted period of control signal TP. By doing so, the video signal of source line DL#1 is converted from positive polarity (the voltage level of video signal higher than the voltage level of VCOM) to negative polarity (the voltage level of video signal lower than the voltage level of VCOM). The video signal of source line DL#2 is converted from negative polarity to positive polarity. When polarity converts, large range of voltage level change occurs. Because power consumption has direct ratio to the voltage level change, larger range of voltage level change causes higher power consumption.